programmatically get child nodes referencing parent by entity reference uuid, using loadByProperties & entityTypeManager or other way without views

Question

I tried this answer:

https://drupal.stackexchange.com/a/298084/1082

But I can't seem to use

'field_scientists' => $entity_reference_uuid

where, in my case, field_scientists is a field of type Entity Reference UUID - which is a field type provided by https://www.drupal.org/project/entity_reference_uuid module

What happens for me is that I get nothing back, my results array from that example is empty.

Looking to do this programmatically in my own custom module, rather than use a Drupal View.

If there's another way e.g. that uses the ->query method for querying the database I'd be happy to use that programmatic approach.

Thank you.

Update

An example of a uuid of a node in my case is BMSSYS0000051988.

This was set in a migration import from a field in a CSV.

My attempts are:

1. based on the example in the other question: https://drupal.stackexchange.com/a/298084/1082

  $nodes = \Drupal::entityTypeManager()->getStorage('node')->loadByProperties([
    'type' => 'bol',
    'field_parent_uuid' => $taxonkey,
  ]);

2. db query

$query = \Drupal::entityQuery('node')
->condition('status', NODE_PUBLISHED)
->condition('type', 'bol');
$and = $query->andConditionGroup();
$and->condition('field_parent_uuid',  $taxonkey);
$query->condition($and);
$result = $query->execute();

where $taxonkey is BMSSYS0000051988

both 1 and 2 attempts above return an empty array.

Update 2

here is my migration config that shows uuid being written to from a field in the csv. Is this legal? Should a developer's code change the uuid value or should uuid only be handled by Drupal core?

dependencies: {  }
id: bol_csv_import
class: null
field_plugin_method: null
cck_plugin_method: null
migration_tags: null
migration_group: defaultl: publicbins
label: 'Import bol species data'
source:
  plugin: csv
  path: ./data/taxonomy_species_with_unpacked_bold.csv
  delimiter: ','
  enclosure: '"'
  header_offset: 0
  ids:
    - uuid
  fields:
    -
      name: uuidl: publicbins
      label: 'NBN id'
    -
      name: parent_uuid
      label: 'NBN id of parent'
    -
      name: name
      label: Name
    -
      name: rank
      label: 'Taxonomic Rank'
    -
      name: taxon_key
      label: 'Taxon Key'
    -
      name: authority
      label: authority
    -
      name: specimenrecords
      label: specimenrecords
    -
      name: publicrecords
      label: publicrecords
    -
      name: publicbins
      label: publicbins
    -
      name: taxid
      label: 'NBN Taxon ID'
process:
  title: name
  uid:
    plugin: default_value
    default_value: 1
  uuid: uuid
  field_parent_uuid: parent_uuid
  field_taxon_key: taxon_key
  field_authority: authority
  field_rank: rank
  field_num_bold_barcode_specimens: specimenrecords
  field_num_bold_public_records: publicrecords
  field_num_bold_public_bins: publicbins
  field_bold_taxon_id: taxid
  type:
    plugin: default_value
    default_value: bol
destination:
  plugin: 'entity:node'
migration_dependencies: null

Update 3

I'll write a db query to solve this issue. Running a command line sql indicates this approach could work:

MariaDB [db]> select * from node where nid = 246;
+-----+------+------+------------------+----------+
| nid | vid  | type | uuid             | langcode |
+-----+------+------+------------------+----------+
| 246 |  248 | bol  | NBNORG0000041189 | en       |
+-----+------+------+------------------+----------+
1 row in set (0.001 sec)

Answer 1

In theory this should work, the field type sets the UUID as main property: EntityReferenceUuidItem:: mainPropertyName()

It might be that Drupal is confused and handling the field as a standard entity reference field because it extends the core field type.

To make clear which field property you are querying append it with a dot:

'field_scientists.target_uuid' => $entity_reference_uuid

Which should work for both, loadByProperties or an entity query:

->condition('field_scientists.target_uuid', $entity_reference_uuid)

The first is only a shortcut for the second using the same query engine.